The biggest ever symphony; smoking on stage; Ben Mezrich

With Mark Lawson.

Havergal Brian's epic Gothic symphony demands a vast orchestra, choirs and unusual percussion effects. Conductor Martyn Brabbins discusses how he's leading 1000 musicians and performers through this rarely-heard piece, in a performance at the BBC Proms on Sunday.

Ben Mezrich's book about the founding of Facebook inspired the Oscar-winning film The Social Network. His new book also focuses on a true story: Sex on the Moon is the tale of the daring theft of lunar rocks from NASA. Mezrich reflects on the art and the ethics of writing non-fiction in the style of fiction.

A London theatre recently warned its audiences that the actors would be smoking on stage for much of the evening. Mark reports on why the theatre is allowed to remain a public building which permits smoking, including the views of actors Kristin Scott Thomas and Dominic West and director Simon Godwin.